Dual circuit breaker construction



June 6, 1961 M. MALLORY, JR

DUAL CIRCUIT BREAKER CONSTRUCTION 7 Filed July 6, 1959 'f\ in jINVENTOR.

z MARION MALLOZYJE.

WILSON, LEW/5 M EAE United States Patent O 2,987,589 DUAL CIRCUITBREAKER CONSTRUCTION Marion Mallory, Jr., Detroit, Mich., assignor toThe Mallory Research Company, Detroit, Mich. Filed July 6, 1959, Ser.No. 825,342 2 Claims. (Cl. 200-30) This invention relates to internalcombustion engine spark timing mechanisms, and particularly to engineignition systems employing dual point circuit breaker mechanisms.

In the conventional dual point circuit breaker arrangement thedistributor shaft cam surfaces are engaged with two separate breakerarms, each controlling a set of contacts. The breaker arms are relatedto one another in such manner that one set of contacts is opened priorto the other set of contacts with an overlapping period in which both ofthe contacts are closed. The two circuit breakers are arranged inparallel so that one circuit breaker opens the circuit and the otherbreaker closes the circuit. The arrangement is characterized by lack ofcorrosion scale or pitting of the contacts. Also, the current is enabledto better saturate the primary winding of the coil than in the casewhere only a single circuit breaker is employed. With the dual circuitbreaker system the breaker contacts can be highly gapped which preventsexcessive flashing and shortened service life.

In spite of the advantages of the dual circuit breaker arrangement overthe conventional single circuit breaker arrangement the dual circuitbreaker arrangement has sufiered to a certain extent by reason of itshigher cost. Thus, in the conventional dual circuit breaker arrangementeach circuit breaker requires a separate mounting construction for thebreaker arm, as well as a separate mount for each fixed contact and aseparate mounting structure for the two leads to the individualbreakers. Also, the separate breakers have been mounted on separatesupport brackets which have had to be adjusted with respect to oneanother in order to secure a proper timing. Such adjustments are timeconsuming, and have the possibility of working out'of position so as todestroy the proper timing.

With the above factors in mind, it is a primary object of the presentinvention to provide a dual circuit breaker construction wherein thecost of manufacture and installation is reduced as compared with thecost involved in the conventional dual circuit breaker arrangement.

It is a further object of the invention to provide a dual circuitbreaker structure wherein both breaker arms are fulcrumed on the samesupport element so that one breaker arm can never move out of adjustmentwith respect to the other breaker arm.

An additional object of the invention is to provide a dual circuitbreaker arrangement wherein the components may be assembled togetherwithout possibility of improper adjustment of the parts.

A further object of the invention is to provide a dual circuit breakerarrangement wherein the leads can be economically mounted therein.

Other objects of this invention will appear in the following descriptionand appended claims, reference being had to the accompanying drawingsforming a part of this specification wherein like reference charactersdesignate corresponding parts in the several views.

In the drawings:

FIGURE 1 is a plan view of one embodiment of the invention.

FIG. 2 is a view taken substantially on line 2-2 in FIG. 1.

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited in its employed herein isfor the purpose of description and not of limitation.

Referring to the drawings, there is shown an internal combustion enginetiming system including a distributor casing 10 rotatably mounting thedistributor shaft 12.

V Shaft 12 carries the cams 14 which sequentially engage the'breakerarms of the circuit breaker construction gen: erally indicated bynumeral 16.

Circuit breaker structure 16 comprises a bracket 18 secured to thegrounded plate 20 by means of screws 22. Bracket 18 is provided with anintegral upstanding wall 24, and a second integral upstanding wall 26.Projecting upwardly from bracket 18 is av post structure 28 which servesas a fulcrum for the two breaker arms 30 and 32. Arm 32 is positionedalmost directly beneath arm 30 and is thus not completely visible inFIG. 1.

However, arm 32 is contoured similarly to arm and the description of arm30 will therefore generally apply for a description of arm 32.

Breaker arm 30 comprises a fiber portion 34 and a I metallic portion 36,the two portions being secured together by means of the metal rivets 38.Rivets 38 also extend through the end portion of. a metallic leaf spring40, said spring having its other end portion 42 engaged against aninsulator 44 located on the upstanding arm 26 of bracket 18. A secondinsulator 46 may be provided for electrically isolating arm 26 from thelead 48. A rivet 52 is extended through the overlapped portions as shownin FIG. 1 to anchor the spring 40 relative to the arm 26 and toelectrically interconnect the lead 48 with the spring. Lead 48 extendsfrom a terminal structure 53 which may include insulator member 54having a screw-type terminal 56 therein. The outer end portion of screwterminal 56 is adapted to receive the lead from the conventional sparkcoil (not shown).

A second terminal structure is provided at 58 for ,con-' nection with asecond line leading from the spark coil, the arrangement being such thatthe two terminal structures 53 and 58 are connected in parallel witheach other. Terminal structure 58 connects to a lead 50 which extendsinto electrical connection with the leaf spring 62 for the lower circuitbreaker arm 32. A rivet and two insulators (similar to the elements 52,44 and 46 shown in FIG. 1) are employed for connecting the conductor 50to the spring 62, these elements also serving to mount the spring on theupstanding arm portion 26. Spring 62 is of generally the same curvatureas spring 40, and is directly below spring 40 so that it is not visiblein FIG. 1. As previously noted, the lowermost circuit breaker arm ispositioned directly below circuit breaker arm 30, the lower circuitbreaker comprising a fibrous portion substantially directly beneathfibrous portion 34, and a metallic portion 64 substantially directlybeneath metallic portion 36. Each of the metallic arm portions 36 and 64carries a contact button 68 registering with a contact button 70 carriedon the upstanding arm 24. It will be appreciated that there are providedtwo sets of contacts, with each set of contacts being opened and closedby iL'S cooperating breaker arm.

Each breaker arm is provided with an extension 72 or 74 adapted toengage the cam surfaces 14 during high speed rotation of shaft 12. Thearrangement is such that the upper breaker arm has its portion 72engaged by the cam lobe slightly before engagement of the extension 74on the lower breaker arm. As each extension is engaged by the camsurface its breaker arm is moved away from the axis of shaft 12 so as toopen its contact at 68. The

spacing or offsetting of the extensions 72 and 74 causes the contactscontrolled by thelower breaker arm to be opened after opening of theupper set of contacts.

The initial current flow through the apparatus takes place via theterminal structure 53, lead 48, spring 40, the upper set of contacts 68and 70, arm 24,the flat portion of bracket 18, and the grounded plate20. When both sets of contacts are closed part of the current from thecoil primary flows through terminal structure 58, conductor 50,lowermost spring 62, the lowermost breaker arm portion 64, the lowermostset of contacts, bracket portions 24 and 18, and grounded plate 20.During'the period when the lower breaker arm contacts are closed and theupper breaker arm contacts are opened, the entire current from the coilflows through the terminal structure 58.

The arrangement is such that the'lowerjset of contacts open the circuit,and the upper'set of contacts close the circuitso that corrosion, scaleor pitting of the contacts is avoided. The overlapping closed periodis'such asto provide a good electrical circuit such as to obtain asatisfactory coil saturation withthe provision of a hot high voltagespark after collapsing of the magnetic field in the coil core.

It will be noted that'with the illustrated arrangement both of thecircuit breaker arms are fulcrumed on a single post 28. Also, only asingle support arm 24 is provided for the two fixed contacts, and asingle upstanding arm 26 is only required to mount the two ,leaf'springs40 and 62 and the leads 48 and 50. The arrangement of parts ischaracterized by a simplicity of construction which lends itself tomanufacture at relatively low cost. Also, since both circuit breakerarms are fulcrumed on the same post structurethe extensions72 and 74 are'at all times correctly positioned relative to one another so as toobtain the proper timing. This is in contrast to the usual dual circuitbreaker arrangement wherein the individual circuit breaker arms aremounted on separate bracket structures requiring precise adjustmentrelative to one another.

While a specific bracket structure and'arrangement has been shown in thedrawings, it will be appreciated that modification thereof may be madewhile still operating within the teachings of the invention as definedin the accompanying claims.

I claim:

1. In an ignition timing circuit the combination comprising a circuitbreaker structure including a bracket having first and second upstandingwalls; a post structure carried on said bracket and extending'parallelto the upstanding walls; first and second circuit breaker arms fulcrumedat points on said post structure spaced from each other and from thebracket structure so that each arm is free to pivot on the poststructure without frictional interference from the other arm or bracketstructure; a first leaf spring anchored at one of its ends on said firstwall and having its other end connected with the first breaker arm forsupporting it on the post structure; a second leaf spring having one ofits ends anchored on said first wall and having its other end connectedwith the second breaker arm for supporting said second breaker arm onthe post structure; a contact carried by each of said breaker arms inalignment with a portion ofthe second wall; and a contact carried on thesecond wall in alignment with each of said first-mentioned contacts.

2. The combination of claim 1 wherein each of the circuit breaker armscomprises a one-piece molded element defining a U-shaped socketengageable with the post structure, a fiat wall portion extending fromsaid socket, and a cam-engageable projection extending angularly fromthe fiat wall portion; each of said breaker'arms further comprising anelongated metallic contact mount positioned against one surface of theflat wall portion; each of said leaf springs having a portion thereofengageable with another face of its respective fiat wall portion; andthe combination'further comprising electrically conductive fastenermeans extending through each leaf spring, its fiat wall portion, andcontact mount whereby to electrically and mechanically connect the leafspring with its breaker arm.

References Cited in the file of this patent UNITED STATES PATENTS1,568,112 Voge Ian. '5, 1926 2,167,366 Mallory July 25, 1939 2,270,982Vanderpoel et al. Jan. 27, 1942 2,529,480 Booth Nov. 14, 1950 2,696,534Mallory Dec. 7, 1954 2,697,762 Burch Dec. 21, L954

